yacen

yacen is a simple chess engine with main focus on understandability of code and mechanisms rather than on pure performance.
It is completely written in ANSI-C using nothing more than the standard library and thus is very portable and easy to compile on almost every platform.
http://sourceforge.net/projects/yacen/

"IMPORTANT: I renamed the project to cengix (chess engine no. x). See http://code.google.com/p/cengix.

IMPORTANT: yacen is not in any way related to the YACE chess engine. The similar name was a mistake."

http://sourceforge.net/projects/yacen/